N1-methylnicotinamide In Urine Research Articles

Automated and manual determination of N1-methylnicotinamide in urine

An automated AutoAnalyzer method and a manual adaptation of the automated method are described for determining N1-methylnicotinamide (NMN) in urine. The new methods incorporate improvements presented by Pelletier and Campbell (Anal. Biochem. 3:60, 1962) for the fluorometric determination of NMN after condensation with methyl ethyl ketone (MEK). The new methods are simpler and not limited by the usage of a single brand of MEK. Various brands of MEK into which hydrogen peroxide had been added in order to catalyze the formation of the condensation product were used and found to give comparable NMN values with different urine specimens. Results of the analysis of 21 urine specimens by the new procedures agreed well with those by the method of Carpenter and Kodicek (Biochem. J. 46: 421, 1950) for which interpretation guidelines exist. Furthermore, it was found that eluates from the chromatographic purification of thiamine in urine with Decalso retained the NMN present in the original specimens, gave complete recoveries of added NMN and were free from nearly all interfering fluorescing substances; this purification would be advantageous for determining with accuracy and precision NMN levels in the urine of deficient subjects and could be used routinely when thiamine analysis has to be performed.

Determination of N1-methylnicotinamide in urine by high-pressure liquid chromatography.

This paper reports a precise method that is shorter than previously reported methods for the quantitative determination of N1-methylnicotinamide (MNA) in urine. The method employs a single column chromatographic isolation step, followed by high-pressure liquid chromatographic (HPLC) analysis. Potential interfering substances present in urine are removed during the column chromatography step. The combined MNA fractions eluted from this column were collected and concentrated for quantitative assay of MNA by HPLC. HPLC analysis was effected in less than 15 min using a strong cation- exchange column eluted with 0.25 M ammonium dihydrogen phosphate (pH 4.3). Linearity of MNA detection by HPLC at 254 nm extended below 20 ng, with an average recovery of 101% for 150, 250 and 500 microgram MNA added to 5 ml or urine.

Studies on tryptophan-niacin metabolism in streptozotocin diabetic rats.

Streptozotocin diabetic male albino rats were observed to exhibit faulty conversion of tryptophan into niacin. Streptozotocin-injected rats, kept on niacin-deficient diet and given a dose of L-tryptophan (intraperitoneal or oral) excreted comparatively less quantities of niacin and N1-methylnicotinamide in urine than the control nondiabetic rats. Rats continued to show this effect for at least three months after streptozotocin injection. Dietary intake was found to have no influence on the excretory pattern. Streptozotocin diabetic rats were also observed to excrete greater amounts of xanthurenic acid and other tryptophan metabolites on tryptophan administration as compared to the nondiabetic rats.

Synthesis and metabolism of quinolinic acid ring labeled with tritium.

Summary1. Quinolinic acid was labeled in the 4, 5, and 6 positions with tritium by the neutron recoil method. 2. Intraperitoneal injection of labeled quinolinic acid into rats was followed by excretion of labeled N1 methylnicotinamide in urine during the next 24 hours. Tritium contents of excreted N1 methylnicotinamide in 2 experiments indicated that 7.6 and 23.6% originated from the injected labeled quinolinic acid. The evidence is definite that quinolinic acid can serve in the rat as a source of niacin. 3. Most of the injected quinolinic acid was exreted as such in the urine. Quinolinic acid isolated from urines of 2 rats had specific activities of 103 and 112% of injected quinolinic acid. The increase in specific activity suggests that tritium-labeled quinolinic acid may have been less rapidly metabolized than the unlabeled substance.

A simple method for the determination of N1-methylnicotinamide in urine.

1. A rapid and simplified method for the estimation of MNA is presented.2. The conditions of the reaction, especially the effect of the amount of water and of the mixture of KCl-HCl solution are studied.3. The duration of the condensation reaction in an alkaline medium is also important, and the appropriate conditions are reported.4. Throughout the experiments the temperature of the hot water bath was kept at 85-90°. Instead of a boiling water bath, rather lower temperature was adopted for the convenience of handling a number of samples at a time to prevent spattering effect of the solution while heating and to maintain rather uniform temperature for the chromatographic procedure.5. A linear relationship between the concentration of MNA and fluorometer reading on a logarithmic plot has been established.6. An inadequacy of the use of internal standards is discussed.7. By adopting the new method here proposed, time for operation can be shortened markedly, thus enabling the estimations of 50 urine samples in a day.

Excretion of N1-methylnicotinamide and the 6-pyridone of N1-methylnicotinamide in urine of human subjects.

SummaryEssentially normal subjects maintained for short periods on diets low in nicotinamide and tryptophan excrete approximately 3 mg of N1-Me and 5 mg of pyridone per day. Following an oral 50 mg test dose of nicotinamide; the average increase in excretion of N1-Me is 5.5 mg and that of pyridone, 23.4 mg. The excretion of N1-Me following the test dose rises rapidly during the first 4 hours and decreases to basal levels within 24 hours; pyridone is excreted more slowly the first few hours but appears in large amounts later in the day. After graded doses of nicotinamide, the excretion of pyridone increases more rapidly than does that of N1-Me. In subjects with pellagra, the excretion of these metabolites is lower both on standard diets and following administration of small doses of nicotinamide. These data suggest procedures that may be of use in evaluating niacin nutrition.

Hydrogen-ion concentration of solutions of the carbonates of calcium

Malnourished patients with the acquired immunodeficiency syndrome (AIDS) can develop pellagra-like manifestations such as dermatitis, diarrhea, and dementia; therefore, we tested the hypothesis that patients with AIDS and diarrhea would have niacin depletion. This study compared 24-h urine excretion of N1-methyl-nicotinamide (N1MN) among patients with pellagra and patients with AIDS who did and did not have diarrhea.Three groups were studied: G1 (patients with AIDS and diarrhea, n = 5); G2 (patients with AIDS and no diarrhea, n = 7), and G3 (patients with alcoholic pellagra and without the human immunodeficiency virus, n = 8). Diarrhea was defined as the production of at least three liquid stools per day over 3 to 5 d. Studies included mucosal intestinal biopsy, malabsorption tests, detection of parasites in stool, and serum albumin measurements. Semiquantitative food-frequency questionnaire, anthropometry, and daily urinary N1MN excretion were also determined. Groups were matched in relation to age, sex, presence of parasites in stool, and intestinal absorption results.G1 had normal intestinal examination by light microscopy and no parasites in stools. G2 group showed lower levels of serum albumin (2.6 ± 0.3 g/dL) when compared with G1 (3.4 ± 0.3 g/dL) and G3 (3.1 ± 0.7 g/dL). Except for patients with pellagra, groups met their energy requirements. Patients in G3 (0.013, 0.01–0.081 mg/dL) and G1 (0.062, 0.001–0.33 mg/dL) excreted smaller amounts of N1MN in urine than did those in G2 (0.63, 0.02–2.9 mg/dL).Patients with AIDS and diarrhea excreted less N1MN in urine than did those without diarrhea. These patients may have an impaired niacin nutritional status, possibly associated with increased metabolic needs.